Fetal Heart Block: A New Experimental Model to Assess Fetal Pacing

Epicardial fetal pacing via thoracotomy has the potential of being a safer and more reliable procedure to treat congenital complete heart block (CHB) associated with fetal hydrops refractory to medical therapy. To assess the acute electrophysiological characteristics of two ventricular epicardial leads, a new experimental model of fetal heart block induced by cryosurgical ablation of the AV node without the need for fetal cardiac bypass was performed in 12 pregnant ewes at 110–115 days gestation. A modified screw-in lead (1½ turns) was used in six fetal lambs and a stitch-on lead in the other six lambs. CHB was achieved in 100% of the fetal lambs, with no ventricular escape rate noticed in any of the lambs. The acute stimulation thresholds were consistently low for both leads, with lower values for the screw-in lead at pulse duration below 0.9 msec (P < 0.03). Current measured at voltage threshold with pulse width below 0.5 msec was lower for the screw-in lead (P < 0.048). Stimulation resistance, measured during constant-voltage pacing, was not statistically different between the two leads (441.8 ± 13.7 Ω for the screw-in lead vs 480.2 ± 59.2 Ω for the stitch-on lead). No significant differences (P > 0.20) were found in R wave amplitude between the two electrodes. Slew rates were significantly higher in the screw-in group than in the stitch-on group (1.40 ± 0.2 vs 0.62 ± 0.2 V/sec, P = 0.04). This model of CHB is a simple and reproducible method to assess fetal pacing. We find the screw-in electrode to be a better option when fetal pacing is indicated.     

Fetal cardiac function evaluation: A review

The aim of this review is to provide an up to date on the current use of fetal echocardiography in assessing the fetal cardiac function and its potential research and clinical applications. Despite classically is been used for prenatal diagnosis of fetal heart defects, assessment of fetal cardiac function has been recently proposed as a fundamental tool to assess pregnancies complicated by several disorders with long-term impact on post-natal cardiovascular health, such as placental insufficiency and fetal growth restriction. In this review we present anatomical and functional fetal cardiac development mechanisms and an overview of the currently available techniques for evaluating fetal heart function.     

Utility of Fetal Echocardiography After Normal Cardiac Imaging Findings on Detailed Fetal Anatomic Ultrasonography

Objective. The purpose of this study was to assess the utility of fetal echocardiography (FE) after normal fetal cardiac imaging findings during detailed fetal anatomic ultrasonography (FAU). Methods. We conducted a retrospective cohort review of obstetric ultrasonographic studies from November 2001 through July 2005. We identified women with a singleton gestation with increased risk for congenital heart disease who received FAU performed by a maternal‐fetal medicine specialist at 16 to 20 weeks' gestation with subsequent FE. These records were compared with newborn outcomes. Results. Of 789 pregnancies that had FAU and FE, 481 had satisfactory cardiac imaging. Of those, only 1 fetus had abnormal FE findings. After delivery, 4 of the 480 neonates with normal FAU and FE findings had a diagnosis of a heart defect. Conclusions. Fetal echocardiography does not substantially increase the detection rate of major cardiac anomalies after normal findings on detailed FAU performed by a maternal‐fetal medicine specialist.     

Role of HDLive in Imaging the Fetal Heart

HDLive is a rendering methodology that generates realistic images of the human fetus from sonographic data. The objective of this study is to demonstrate the utility of high‐definition live in evaluating fetal heart especially in the first trimester (11–14‐week) scan. The normal atrioventricular valve and its abnormalities along with septal defects can be vividly demonstrated with this technique, and eight cases with cardiac defects are illustrated. Its use in the first‐trimester evaluation of heart would give a better perspective of the cardiac malformation, which provides the opportunity for counseling options early in pregnancy.     

Fetal anatomic and functional echocardiography: a 5-year review.

OBJECTIVE: To assess the concordance of fetal and postnatal echocardiography when congenital heart disease is suspected prenatally. METHODS: The perinatology and pediatric cardiology ultrasound databases were searched for fetal echocardiograms obtained between June 1995 and June 2000. All cases with abnormal fetal echocardiographic findings in which postnatal echocardiography was performed were included. A perinatologist, pediatric cardiologist, or both interpreted all fetal echocardiograms; a pediatric cardiologist interpreted all postnatal echocardiograms. The fetal and postnatal echocardiograms were compared for the presence of 25 specific components. The kappa statistic was calculated to evaluate concordance between fetal and postnatal studies. Positive and negative predictive values for fetal studies were calculated under the assumption that the postnatal study yielded the correct diagnosis. RESULTS: Sixty-five patients were included. Congenital heart disease ranged from an isolated atrial septal defect to complex disease. Images adequately showed all 25 components in more than 85% of the fetal studies. Concordance between fetal and postnatal echocardiograms was excellent (kappa > 0.75) for 20 of the 25 components evaluated. Four of the remaining 5 components had fair concordance (kappa = 0.4-0.75) between fetal and postnatal studies. Structural abnormalities without excellent concordance included partial anomalous pulmonary venous return, secundum atrial septal defects, and heart malposition. Concordance between fetal and postnatal right and left ventricular function was fair; however, differences may have been due to physiologic changes that occurred after birth rather than to inferior diagnostic accuracy of fetal echocardiography. CONCLUSIONS: Fetal echocardiography is an extremely useful and accurate clinical tool for prenatal and postnatal evaluation of congenital heart disease.     

Collaborative Study on 4‐Dimensional Echocardiography for the Diagnosis of Fetal Heart Defects

Objective. Congenital anomalies are the leading cause of infant mortality in the United States, and congenital heart defects (CHDs) are the most common type of birth defects. Recently, 4‐dimensional ultrasonography (4DUS) with spatiotemporal image correlation (STIC) has been introduced for fetal echocardiography. Accumulating evidence indicates that 4DUS with STIC may facilitate the examination of the fetal heart. Our objectives were to determine the accuracy of 4DUS for the diagnosis of CHDs and the agreement among centers. Methods. This study included 7 centers with expertise in 4D fetal echocardiography. Fetuses with and without confirmed heart defects were scanned between 18 and 26 weeks, and their volume data sets were uploaded onto a centralized file transfer protocol server. Intercenter agreement was determined using a κ statistic for multiple raters. Results. Ninety volume data sets were randomly selected for blinded analysis. Overall, the median (range) sensitivity, specificity, positive and negative predictive values, and false‐positive and ‐negative rates for the identification of fetuses with CHDs were 93% (77%–100%), 96% (84%–100%), 96% (83%–100%), 93% (79%–100%), 4.8% (2.7%–25%), and 6.8% (5%–22%), respectively. The most frequent CHDs were conotruncal anomalies (36%). There was excellent intercenter agreement (κ = 0.97). Conclusions. (1) Four‐dimensional volume data sets can be remotely acquired and accurately interpreted by different centers. (2) Among centers with technical expertise, 4DUS is an accurate and reliable method for fetal echocardiography.     

Interdisciplinary Team Huddles for Fetal Heart Rate Tracing Review

To address an increase in unexpected poor outcomes in term neonates, our team developed a goal of high reliability and improved fetal safety in the culture of the Labor and Delivery nursing department. We implemented interdisciplinary reviews of fetal heart rate, along with a Category II fetal heart rate management algorithm and a fetal heart rate assessment rapid response alert to call for unscheduled reviews when needed. Enhanced communication between nurses and other clinicians supported an interdisciplinary approach to fetal safety, and we observed an improvement in health outcomes for term neonates. We share our experience with the intention of making our methods available to any labor and delivery unit team committed to safe, high-quality care and service excellence.     

Aorta Larger Than Pulmonary Artery in the Fetal 3‐Vessel View

Objective. Fetal great artery asymmetry may accompany congenital heart disease. The fetal echocardiographic 3‐vessel view (3VV) allows assessment of the superior vena cava, ascending aorta (AA), and main pulmonary artery (MPA). Our aim was to determine the association of congenital heart disease in fetuses with an AA/MPA ratio of greater than 1. Methods. We electronically searched our fetal echocardiographic database for studies performed between March 2002 and January 2008 that showed 3VVs with AA/MPA ratios of greater than 1 and correlated the findings with the presence of congenital heart disease. Results. In 2797 fetal echocardiograms, we identified 31 fetuses with normal 4‐chamber views showing AA/MPA ratios of greater than 1 in the 3VV. Of 31 fetuses, 25 (81%) had tetralogy of Fallot (ToF) or a ToF variant, and 6 (19%) had an aortic valve abnormality or isolated dilatation of the AA. Conclusions. Screening obstetric fetal sonography showing a 3VV AA/MPA ratio of greater than 1 suggests congenital heart disease and indicates the need for comprehensive fetal echocardiography.     

Evaluation of Referral Indications for Fetal Echocardiography in Beijing

Objectives. This study was conducted to evaluate the referral indications for fetal echocardiography (FE) in a tertiary center and to determine which indications were significantly associated with prenatal detection of congenital heart disease (CHD). Methods. The medical records of 1425 consecutive women who underwent second‐ and third‐trimester FE at the Ultrasound Center of Beijing Obstetrics and Gynecology Hospital from March 2003 to December 2007 were reviewed. Referral indications, FE diagnoses, and pregnancy outcomes were collected. Univariate and multivariate logistic regression analyses were performed to identify those referral indications associated with prenatal detection of CHD. Results. In 126 patients (8.8%), CHD was detected prenatally and confirmed postnatally. Logistic regression analysis showed that abnormal cardiac views and extracardiac malformation findings (especially a single umbilical artery) on second‐trimester ultrasound screening were found to have significantly more CHD (P < .001). The adjusted odds ratios were 15.2 (95% confidence interval, 9.85–23.45) and 6.78 (95% confidence interval, 2.38–19.27), respectively. Conclusions. Abnormal cardiac views and extracardiac malformation findings on second‐trimester ultrasound screening were significantly associated with prenatal detection of CHD.     

Two‐Dimensional Speckle Tracking of the Fetal Heart

Various approaches to 2‐dimensional speckle tracking have been used to evaluate left ventricular function and deformation in the fetus, child, and adult. In 2015, because of differences in imaging devices and analytical programs, the cardiology community published a consensus document proposing standards for pediatric/adult deformation imaging using 2‐dimensional speckle tracking. The understanding and application of deformation imaging in the fetus have been limited by a lack of uniform software, terminology, techniques, and display. This article provides a practical, step‐by‐step approach for deformation analysis of the fetal heart using offline software that is independent of specific ultrasound vendors.     

多普勒超声心动图对胎儿充血性心衰的研究

目的应用多普勒超声心动图研究、探讨胎儿充血性心力衰竭(CHF)的病变机制,为早期宫内诊断和治疗及疗效评价提供准确依据。方法超声心动图检出并诊断41例CHF胎儿及正常对照组50例。结果(1)41例胎儿中先天性心脏病14例;重症心律失常15例,胎儿肿瘤5例,双胎输血综合征5例和胎儿贫血2例;(2)均出现胎儿水肿;心脏显著肥厚扩大,表现为心胸比例增大,心房、心室的不对称增大或心肌肥厚。心室缩短率(FS%)及心输出量(CCO)降低(P<0.001);(3)中至重度二、三尖瓣返流(MRTR),9例肺动脉瓣返流;(4)32例胎儿脐动脉PI值增高或舒张期血流相消失及大脑中动脉PI值降低。37例出现脐静脉搏动性血流及41例均示下腔静脉内径增宽及血流频谱改变。结论应用多普勒超声心动图评价胎儿CHF的导致因素,通过主动脉和肺动脉CO的总和CCO可无创获得心输出量的指标及计算FS以达到量化胎儿心功能的目的。可直观地显示胎儿心脏结构,检测瓣膜返流及评价外周血流动力学变化。     

胎儿心脏病血流动力学的彩色多普勒超声心动图评价

1992年2月至1994年11月应用彩色多普勒超声心动图检测胎儿心脏364例。检出胎儿心脏病7例,其中心脏大血管发育异常6例,心肌病1例。结果显示心脏大血管发育异常及心肌病可使胎儿血流动力学发生明显改变。彩色多普勒超声评价各瓣口及大血管血流速度,速度积分、压力阶差等参数与正常同龄胎儿比较有明显差异。结论彩色多普勒超声心动图对心脏大血管异常血流的显示提供了胎儿血流动力学在胎儿心血管病时的诊断依据,表明胎儿心血管病对胎儿心脏结构及功能的影响。     

胎儿超声心动图在胎儿先天性心脏病产前诊断中的临床价值

目的 探讨胎儿超声心动图在产前诊断胎儿先天性心脏病的临床意义。方法 选择妊娠＞16周,分娩前有高危倾向的孕妇310例行胎儿超声心动图检查。检查中着重观察胎儿腹部切面、胎儿四腔心切面、胎儿左右室流出道长轴或大动脉短轴切面、胎儿主动脉弓长轴切面。结果 共发现9例先天性心脏病胎儿,其中复杂先天性心脏病7例、单纯室间隔缺损1例、1例出生前未确诊,出生后诊断为法洛四联症。敏感性82％,特异性100％。结论 胎儿超声心动图早期诊断胎儿畸形,评价胎儿心功能的有用工具。其诊断的准确性受孕妇体形、胎儿体位以及检查者的经验积累等多方面因素的影响。